He was shot by gunmen in September 2003. Two men were arrested and charged but were later acquitted in 2005. The TJRC report concluded that Dr Mbai was killed because of his political views about devolution. In May 2013, the commission gave the Director of Public Prosecution 18 months to unravel the mystery surrounding the killing of the university don, and the subsequent cover-up in the investigation. The investigation is yet to unravel anything, 15 years later.